Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
thanh vi » hanh vi, thanh va, thanh ve
cua tre » cua te, cuu tre, cua triet
duc ban » duc tan, duc van, dua ban
cau duc » cao duc, cau luc, chu duc
su sach » so sach, vu sach
sach tu » sach thu, cach tu, sach ty
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
van cau » van dau, van hau, van chat

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach tu ((nang xa) OR (lang xa)) hoi. hieu van cau duc ban thanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu ((nang xa) OR (lang xa)) hoi. hieu van cau duc ban thanh vi ((cua tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach tu ((nang xa) OR (lang xa)) hoi. hieu van cau duc ban thanh vi ((cua tre) or (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su sach tu ((nang xa) OR (lang xa)) hoi. hieu van cau duc ban thanh vi ((cua tre) or (cau tren))*.